Hymenochaete ametzii Olariaga, Márquez-Sanz, Gorjón, Zamora & Salcedo, 2024

Olariaga, Ibai, Márquez-Sanz, Rodrigo, Gorjón, Sergio Pérez, Zamora, Juan Carlos & Salcedo, Isabel, 2024, Hymenochaete ametzii sp. nov. (Hymenochaetales, Basidiomycota), an endangered bark-dwelling species inhabiting old Quercus pyrenaica trees from the Iberian Peninsula, Phytotaxa 669 (3), pp. 194-210 : 199-200

Hymenochaete ametzii Olariaga, Márquez-Sanz, Gorjón, Zamora & Salcedo , sp. nov.

Figs. 2–4

MycoBank MB 852550

HOLOTYPE: — SPAIN. Madrid: El Escorial, Bosque de la Herrería, 40.57185 -4.15679 (accuracy 20 m), 980 m. a.s.l., on bark of Quercus pyrenaica , leg. J. C. Zamora, B. Zamora & I. Olariaga, 28-Nov-2020, ARAN-Fungi 19941 . Isotype: G 00576165. Ex-type culture: CECT.

Etymology. Referring to “ametz”, the Basque name of Quercus pyrenaica , specific host of the species, and the name of the son of the first author.

Description. Basidiomata annual or biennial, producing a white rot within the bark, effuse-reflexed to dimidiate or cupulate, 4−20 mm broad, effused part 3−7 mm, pilei 240−320 μm thick, broadly fixed to the substratum, gregarious or slightly confluent, soft when hydrated, hard and brittle when dry. Pileus surface uniformly coloured or zonate, tomentose in young pilei, with tomentum erect or appressed, formed by fascicled hyphae, then glabrous but remaining tomentose in the margin, cinnamon brown, then dark chestnut brown (2.5 YR 3/3) and remaining cinnamon brown in the younger margin, with erect scattered setae under high magnification (×20) on the margin. Margin thin, obtuse, sometimes lobate. Hymenium smooth or slightly tuberculate, cinnamon brown (7.5 YR 5/6) to dark cinnamon brown (7.5 YR 4/6), with protruding setae under high magnification (×20). Hyphal system monomitic, septa without clamps. Tomentum layer present in young or actively growing parts, 50−90 μm thick, constituted by hyphal fascicles, up to 230 µm long and 25−40 µm broad, composed of cylindrical hyphae, 2.5−3 μm broad, obtuse, brown, disappearing in weathered basidiomata. Pileal setae up to 88 × 9 µm, somewhat smaller than hymenial setae, pale brown to dark brown. Hyphal layer well-developed, 60−110 μm thick, formed by parallel arranged hyphae, cylindrical, with thickened walls (<0.5 µm), 2−3 μm in diam., some brown and with distant septa, others hyaline and with closer septa. Setal layer thickening, with 1−2 layers, 120−150 μm thick, composed of vertical-arranged hyphae, branched, brown, 2.5−4 µm broad. Subhymenium composed of vertical-arranged hyphae, richly branched, often in open angles, 2.5−4 µm broad. Setae arising from the setal layer and the subhymenium, immersed or protruding up to 75 µm over the hymenium, pointed, (70)82−112(140) × 7−12 μm, sometimes associated with simple hyaline hyphidia, up to 1.5 µm broad. Basidia subcylindrical to suburniform, pale brown with a hyaline apex, with 4 sterigmata, (20)26−30 × 4−5.5 μm. Hyphidia sometimes present, protruding 10−20 µm over the hymenium, hyaline, cylindrical or tapering, sometimes constricted or branched 1−2 times, apically 2−3 µm broad. Basidiospores globose to subglobose, hyaline, thin-walled, those deposited on the tomentum pale brown and slightly thick-walled, (4)4.5−6(6.5) × 4−5(5.5) μm, Lm=4.7−5.8, W m =4.3−4.9, Q m =1.1−1.2; n = 125/5. Clumps of spheroid crystals, 8−12(18) µm diam., often present in the hyphal and setal layers, especially in old basidiomata.

Culture. Growing on MEA ( Fig. 5 ) 5–8 mm diam. in 60 days at 18 °C, growing superficial and immersed, effuse, flat, tomentose, aerial part very white to very pale yellow-brown, immersed part cinnamon brown, sometimes whitish in the center. Reverse cinnamon brown. Margin regular to sinuous, distinct. Vegetative hyphae cylindrical, sometimes with a sinuous outline or with scattered conical protuberances, septate, without clamps, hyaline to brown, smooth, thin-walled to slightly thick-walled, without exudates, 1–5 μm broad. Globose to broadly claviform intercalary or terminal segments present in the immersed parts of the culture, up to 19 µm broad.

Material examined. SPAIN. Ávila: Piedralaves. Monte Dehesa Avellaneda, 40.329879 -4.711258 (accuracy 10 m), 1028 m.a.s.l. on bark of old Quercus pyrenaica , in Pinus pinaster forest, leg. I. Olariaga, 17-Dec-2022, ARANFungi 19597. Ávila: Piedralaves, Garganta de Retamalejo, 40.3442756 -4.7106895 (accuracy 10 m), 1200 m.a.s.l. on bark of large Quercus pyrenaica , in mixed forest with Pinus pinaster , leg. I. Olariaga, 17-Dec-2022, ARAN-Fungi 19600. Ciudad Real: Puebla de Don Rodrigo, Garganta de los Membrillos, 39.141361 -4.774167 (accuracy 10 m), 595 m. a.s.l. on bark of Quercus pyrenaica , leg. I. Márquez & Márquez R., 3-Jan-2023, RM 1157 ( MACB 125579); 39.141528 -4.773139 (accuracy 10 m), 595 m. a.s.l. RM 1163 ( MACB 125580). Madrid: La Hiruela, Dehesa Boyal de la Hiruela, 41.078521641 -3.448241484 (accuracy 10 m), 1263 m.a.s.l. on bark of large pollarded Quercus pyrenaica , leg. M. Prieto, A. Olariaga & I. Olariaga, 1-Apr-2021, ARAN-Fungi 19933. Salamanca: Casillas de Flores, bosque de la Genestosa. 40.351956745 -6.7790772 (accuracy 10 m), 898 m. a.s.l. bark of large Quercus pyrenaica , leg. S. Pérez- Gorjón, M. Prieto & I. Olariaga, 4-Dec-2022, ARAN-Fungi 19613; 40.3521202 -6.7812516 (accuracy 10 m), ARANFungi 19621. Soria: Cueva de Ágreda, Dehesa del Moncayo, 41.759161 -1.866643 (accuracy 100 m), 1358 m.a.s.l. on bark of large dead Quercus pyrenaica , leg. V. Huete, J. C. Zamora, Rubio L., Paz A., Lavoise C., Prieto M. & Olariaga I., 25-Oct-2015, ARAN-Fungi 20108. Toledo: Navamorcuende, El Piélago, 40.1434968 -4.7363449 (accuracy 10 m), 1224 m.a.s.l. on bark of large living Quercus pyrenaica , leg. I. Olariaga, 17-Dec-2022, ARAN-Fungi 19605. (see Fig. 6 )

Figures

FIGURE 2. Basidiomata of Hymenochaete ametzii (ARAN-Fungi 19941, holotype). Scale bar 20 mm. Photograph I. Olariaga.

FIGURE 3. Basidiomata of Hymenochaete ametzii. A) Inconspicuous basidiomata in dry state (ARAN-Fungi 19933). B) About fifteen basidiomata on the bark of Q. pyrenaica (ARAN-Fungi 19613). C) Close-up of basidiomata (ARAN-Fungi 19613). D) Close-up of basidiomata (ARAN-Fungi 19613). E) Basidiomata showing the hymenium (ARAN-Fungi 19941, holotype). F) Close-up of basidiomata ex-situ (RM1157 (MACB125579)). Scale bars 20 mm. Photographs I. Olariaga (A, B, C, D, E), R. Márquez (F). Some basidiomata are marked with an arrow.

FIGURE 4. Microscopic characteristics of Hymenochate ametzii (ARAN-Fungi 19941, holotype). A) Basidioma section. B) Close-up of the basidioma section. C) Pileal seta. D) Hyphal fascicles from the tomentum of the pileus surface. E) Section showing the upper part of the hyphal layer, the subhymenium and the hymenium. F) Clumps of sphaeroidal crystals between the subhymenium and the hyphal layer. G) Basidiospores. H) Hymenial setae. I) Hymenial setae, with associated hyphidia. Scale bars 10 µm, except for A (100 µm) and B (20 µm). Photographs I. Olariaga.

FIGURE 5. Cultural characteristics of Hymenochaete ametzii (ex-holotype culture, CECT). A) Culture growing on MEA. B) Brown hyphae from the superficial tomentum. C) Sinuous hyphae from the immersed part. D) Intercalary globose segments. E) Terminal globose to broadly claviform segments. Scales 10 mm (A), 10 µm (B, C, D). Photographs I. Olariaga.

FIGURE 6. Distributional map of the host Quercus pyrenaica in the Iberian Peninsula (small green dots) and Hymenochaete ametzii (solid black dots): 1) Salamanca, La Genestosa; 2) Piedralaves, Monte Dehesa Avellaneda; 3) Toledo, El Piélago; 4) Ciudad Real, Garganta de los Membrillos; 5) Madrid, Bosque de la Herrería; 6) Madrid, La Hiruela, and 7) Soria, Dehesa del Moncayo. Green shaded polygon shows the Extent of Occurrence (EOO), according to the IUCN criteria.